826833 6 Mercury NUT, (M6)

Probable Causes
Parameters
Throttle signal
Inlet air restriction
Exhaust restriction
Fuel system
Driven equipment
Valve lash
Injector adjustmentRecommended Actions
Note: If the problem only occurs under certain conditions, test the engine under those conditions. Examples of certain conditions are high engine speed, full load, and engine operating temperature. Troubleshooting the symptoms under other conditions can give misleading results.
Table 1
Troubleshooting Test Steps Values Results
1. Check for Incorrect Configuration Parameters
A. Connect Cat® Electronic Technician (ET) to the service tool connector.
B. Use Cat ET to verify that the correct parameters are being used.
Parameters
Result: The parameters are correct.
Proceed to Test Step 2.
Result: The parameters are not correct.
Repair: Input the correct parameters. Refer to Troubleshooting, "Configuration Parameters" for additional information.
If the problem is not resolved, proceed to Test Step 2.
2. Check the Throttle Signal
A. Connect Cat ET.
B. Use Cat ET to monitor the following:
- "Throttle Position"
C. Verify that the status for "Throttle Position" is stable and that the engine is able to reach high idle speed.
Throttle Signal
Result: The throttle signal is stable.
Proceed to Test Step 3.
Result: The throttle signal is not stable.
Repair: Refer to the appropriate circuit test. Repair or replace damaged components.
If the problem is not resolved, proceed to Test Step 3.
3. Check for a Restriction in the Inlet Air System
A. Check the air filter restriction indicator, if equipped. Refer to the Operation and Maintenance Manual for additional information.
B. Measure the inlet air restriction for each turbocharger. Refer to Troubleshooting, "Inlet Air Is Restricted" for additional information.
Restriction
Result: The inlet air restriction is OK.
Proceed to Test Step 4.
Result: The inlet air restriction is NOT OK. An imbalance in the system is discovered.
Repair: Repair or replace damaged inlet air system components. Equalize the inlet air restriction for each of the turbochargers.
If the problem is not resolved, proceed to Test Step 4.
4. Check for a Restriction in the Exhaust System
A. Measure the exhaust restriction during engine operation with a load. For data that is specific to your engine, refer to the Technical Marketing Information (TMI).
Restriction
Result: The exhaust restriction measurement is OK.
Proceed to Test Step 5.
Result: The exhaust restriction measurement is NOT OK.
Repair: Repair or replace damaged exhaust system components.
If the problem is not resolved, proceed to Test Step 5.
5. Inspect the Fuel System
Refer to Testing and Adjusting, "Fuel System Inspection" for additional information.
A. Visually check the fuel level in the fuel tank. Do not rely on the fuel gauge only.
B. Ensure that the vent in the fuel cap is not filled with debris.
C. Ensure that the fuel supply valve (if equipped) is in the full OPEN position.
Note: Cold weather adversely affects the characteristics of the fuel. Refer to the engines Operation and Maintenance Manual for information on improving the characteristics of the fuel during cold-weather operation.
D. Check fuel quality. Refer to Testing and Adjusting, "Fuel Quality - Test" for additional information. Check the fuel tank for debris or foreign objects which may block the fuel supply.
E. Check for fuel leaks.
Fuel System
Result: The fuel system is OK.
Proceed to Test Step 6.
Result: The fuel system is NOT OK.
Repair: Repair or replace damaged fuel system components.
If the problem is not resolved, proceed to Test Step 6.
6. Inspect the Driven Equipment
Driven Equipment
Result: The driven equipment is OK.
Proceed to Test Step 7.
Result: The driven equipment is NOT OK.
Repair: Repair or replace damaged driven equipment.
If the problem is not resolved, proceed to Test Step 7.
7. Check the Valve Lash
Note: The valve lash can affect the performance of the engine.
Valve Lash
Result: The valve lash is OK.
Proceed to Test Step 8.
Result: The valve lash is NOT OK.
Repair: Reset the valve lash. Refer to Testing and Adjusting, "Valve Lash - Adjust" for additional information.
If the problem is not resolved, proceed to Test Step 8.
8. Check the Fuel Injector Adjustment
A. Refer to Testing and Adjusting, "Fuel Injector Adjustment" for additional information.
Injector Adjustment
Result: The adjustment is NOT OK.
Repair: Correct the adjustment.
Verify that the repair eliminated the problem.
If the procedure did not correct the issue, contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).